Wireless network location techniques

ABSTRACT

Improved wireless network location techniques are described. In one embodiment, for example, an apparatus may comprise circuitry and a communications management module for execution on the circuitry to send a timing announcement element comprising a sounding preamble count parameter indicating a number of sounding preambles, send a null data element comprising a number of sounding preambles equal to the sounding preamble count parameter, receive timing reply information comprising the number of sounding preambles equal to the sounding preamble count parameter, and determine a time of flight based on the timing reply information. Other embodiments are described and claimed.

RELATED CASE

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/766,322, filed on Feb. 19, 2013, the entirety of which is herebyincorporated by reference.

TECHNICAL FIELD

Embodiments described herein generally relate to device locationtechniques for wireless communications networks.

BACKGROUND

In order to determine location information for a particular device in awireless communications network, times of flight for communicationsbetween the device and other devices in the network may be determined.Based on such times of flight, distances may be estimated between thedevice and various other devices that may have known locations. Theseestimated distances may in turn be used to determine an estimatedlocation for the particular device in question. In order to simplify theimplementation of such techniques for determining location information,the times of flight may be determined via the exchange of informationelements conforming to existing defined formats.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one embodiment of a wireless communications network.

FIG. 2 illustrates one embodiment of a first apparatus and oneembodiment of a first system.

FIG. 3A illustrates one embodiment of a first timing informationexchange.

FIG. 3B illustrates one embodiment of a second timing informationexchange.

FIG. 3C illustrates one embodiment of a third timing informationexchange.

FIG. 4A illustrates one embodiment of a fourth timing informationexchange.

FIG. 4B illustrates one embodiment of a first timing announcementelement.

FIG. 4C illustrates one embodiment of a first timing response element.

FIG. 4D illustrates one embodiment of a first transmission diagram.

FIG. 5A illustrates one embodiment of a fifth timing informationexchange.

FIG. 5B illustrates one embodiment of a second timing response element.

FIG. 5C illustrates one embodiment of a second transmission diagram.

FIG. 6 illustrates one embodiment of a second apparatus and oneembodiment of a second system

FIG. 7 illustrates one embodiment of a first logic flow.

FIG. 8 illustrates one embodiment of a second logic flow.

FIG. 9 illustrates one embodiment of a storage medium.

FIG. 10 illustrates one embodiment of a computing architecture.

DETAILED DESCRIPTION

Various embodiments may be generally directed to improved wirelessnetwork location techniques. In one embodiment, for example, anapparatus may comprise circuitry and a communications management modulefor execution on the circuitry to send a timing announcement elementcomprising a sounding preamble count parameter indicating a number ofsounding preambles, send a null data element comprising a number ofsounding preambles equal to the sounding preamble count parameter,receive timing reply information comprising the number of soundingpreambles equal to the sounding preamble count parameter, and determinea time of flight based on the timing reply information. Otherembodiments may be described and claimed.

Various embodiments may comprise one or more elements. An element maycomprise any structure arranged to perform certain operations. Eachelement may be implemented as hardware, software, or any combinationthereof, as desired for a given set of design parameters or performanceconstraints. Although an embodiment may be described with a limitednumber of elements in a certain topology by way of example, theembodiment may include more or less elements in alternate topologies asdesired for a given implementation. It is worthy to note that anyreference to “one embodiment” or “an embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment. The appearances ofthe phrases “in one embodiment,” “in some embodiments,” and “in variousembodiments” in various places in the specification are not necessarilyall referring to the same embodiment.

FIG. 1 illustrates an example of a wireless network 100 such as maycomprise an operating environment for various embodiments. As shown inFIG. 1, a communications device 102 is operative to communicate withcommunications devices 104, 106, and 108 over wireless network 100.Examples of wireless network 100 according to various embodiments mayinclude a wireless local area network (WLAN), a wireless personal areanetwork (WPAN), a wireless metropolitan area network (WMAN), a cellularcommunications network, and a satellite communications network. Theembodiments are not limited to these examples.

In some embodiments, wireless network 100 may operate according to oneor more wireless communications standards. For example, in variousembodiments, wireless network may operate according to Institute ofElectrical and Electronics Engineers (IEEE) Standard 802.11™-2012,published Mar. 29, 2012, titled “Part 11: Wireless LAN Medium AccessControl (MAC) and Physical Layer (PHY) Specifications” (“IEEE802.11-2012”) and/or according to IEEE Draft Standard 802.11ac™/D5.0published Feb. 1, 2013 (“IEEE 802.11ac Revision 5.0”) or according toany predecessors, revisions, or variants thereof. Hereinafter, forpurposes of brevity, embodiments comprising a wireless network operatingaccording to IEEE 802.11-2012 and/or IEEE 802.11ac Revision 5.0 or anypredecessors, revisions, or variants thereof shall be referred to as“802.11” embodiments. It is to be understood that embodiments are bothpossible and contemplated that do not comprise a wireless networkoperating according to either IEEE 802.11-2012, IEEE 802.11ac Revision5.0, or any predecessor, revision, or variant thereof, and that theembodiments are not limited in this context.

In some embodiments, communications device 102 may be operative tocommunicate with communications devices 104, 106, and 108 in order todetermine a location of communications device 102. More particularly,communications device 102 may be operative to communicate withcommunications devices 104, 106, and 108 in order to determine times offlight 111 for communications between communications device 102 andcommunications devices 104, 106, and 108. With respect to any particularcommunication comprising a wireless signal, the term “time of flight” isemployed herein to denote an amount of time taken for the wirelesssignal to travel a distance through a medium, such as from a transmitterthrough air to a receiver. Based on the determined times of flight 111,communications device 102 and/or one or more other devices communicatingover wireless network 100 may estimate respective distances betweencommunications device 102 and communications devices 104, 106, and 108,and estimate a location of communications device 102 based on thoseestimated distances, such as by triangulation, for example. It is worthyof note that although communications device 102 is illustrated ascommunicating with three communications devices 104, 106, and 108 in theexample of FIG. 1, the embodiments are not limited to this example. Insome embodiments, communications device 102 may be operative tocommunicate with and/or determine times of flight 111 corresponding tosmaller or larger numbers of other communications devices, and theembodiments are not limited in this context.

As shown in FIG. 1, communications device 102 may be operative to sendtiming initiation information 103 to each of communications devices 104,106, and 108. It is worthy of note that in various embodiments,communications device 102 may be operative to send different timinginitiation information 103 to each of communications devices 104, 106,and 108, while in other embodiments, communications device 102 may beoperative to send the same timing initiation information 103 to multiplecommunications devices 104, 106, and 108. In response to received timinginitiation information 103, communications devices 104, 106, and 108 maysend respective timing reply information 105, 107, and 109 tocommunications device 102. Communications device 102 and/or one or moreother devices communicating over wireless network 100 may then beoperative to determine times of flight 111 based on the timing replyinformation 105, 107, and 109 received by communications device 102.

Herein, the term “initiator” shall be employed to denote acommunications device that sends timing initiation information 103 toinitiate a process to determine times of flight 111, and the term“responder” shall be employed to denote a communications device thatresponds to such timing initialization information 103 with timing replyinformation 105. For example, as illustrated by the labels in FIG. 1,communications device 102 may comprise an initiator 120 andcommunications device 104 may comprise a responder 130. It is to beunderstood that in the example of FIG. 1, communications devices 106 and108 may also comprise responders, and that communications device 104 islabeled as responder 130 simply for ease of reference below. It isworthy of note that in some embodiments, a particular communicationsdevice may be capable of operation as both an initiator and a responder.For example, although communications device 102 operates as an initiator120 in the example of FIG. 1, communications device 102 may also oralternately operate as a responder 130 within that same wireless network100. The embodiments are not limited in this context.

FIG. 2 illustrates a block diagram of an apparatus 200. Moreparticularly, apparatus 200 may comprise an example of initiator 120 ofFIG. 1 according to various embodiments. As shown in FIG. 2, apparatus200 comprises multiple elements including a processor circuit 202, amemory unit 204, and a communications management module 206. Theembodiments, however, are not limited to the type, number, orarrangement of elements shown in this figure.

In some embodiments, apparatus 200 may comprise processor circuit 202.Processor circuit 202 may be implemented using any processor or logicdevice, such as a complex instruction set computer (CISC)microprocessor, a reduced instruction set computing (RISC)microprocessor, a very long instruction word (VLIW) microprocessor, anx86 instruction set compatible processor, a processor implementing acombination of instruction sets, a multi-core processor such as adual-core processor or dual-core mobile processor, or any othermicroprocessor or central processing unit (CPU). Processor circuit 102may also be implemented as a dedicated processor, such as a controller,a microcontroller, an embedded processor, a chip multiprocessor (CMP), aco-processor, a digital signal processor (DSP), a network processor, amedia processor, an input/output (I/O) processor, a media access control(MAC) processor, a radio baseband processor, an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA), aprogrammable logic device (PLD), and so forth. In one embodiment, forexample, processor circuit 202 may be implemented as a general purposeprocessor, such as a processor made by Intel® Corporation, Santa Clara,Calif. The embodiments are not limited in this context.

In various embodiments, apparatus 200 may comprise or be arranged tocommunicatively couple with a memory unit 204. Memory unit 204 may beimplemented using any machine-readable or computer-readable mediacapable of storing data, including both volatile and non-volatilememory. For example, memory unit 204 may include read-only memory (ROM),random-access memory (RAM), dynamic RAM (DRAM), Double-Data-Rate DRAM(DDRAM), synchronous DRAM (SDRAM), static RAM (SRAM), programmable ROM(PROM), erasable programmable ROM (EPROM), electrically erasableprogrammable ROM (EEPROM), flash memory, polymer memory such asferroelectric polymer memory, ovonic memory, phase change orferroelectric memory, silicon-oxide-nitride-oxide-silicon (SONOS)memory, magnetic or optical cards, or any other type of media suitablefor storing information. It is worthy of note that some portion or allof memory unit 204 may be included on the same integrated circuit asprocessor circuit 202, or alternatively some portion or all of memoryunit 204 may be disposed on an integrated circuit or other medium, forexample a hard disk drive, that is external to the integrated circuit ofprocessor circuit 202. Although memory unit 204 is comprised withinapparatus 200 in FIG. 2, memory unit 204 may be external to apparatus200 in some embodiments. The embodiments are not limited in thiscontext.

In some embodiments, apparatus 200 may comprise communicationsmanagement module 206. Communications management module 206 may compriselogic, circuitry, and/or instructions operative to manage and/orconfigure communications by apparatus 200 over a wireless network 250.In various 802.11 embodiments, wireless network 250 may comprise an802.11 wireless network, and communications management module 206 may beoperative to manage and/or configure communications by apparatus overthat 802.11 wireless network. In some embodiments, communicationsmanagement module 206 may be operative to manage and/or configure onlycommunications by apparatus 200 over wireless network 250. In variousother embodiments, communications management module 206 may be operativeto manage and/or configure communications by apparatus 200 over one ormore other networks in addition to communications by apparatus 200 overwireless network 250. The embodiments are not limited in this context.

FIG. 2 also illustrates a block diagram of a system 240. System 240 maycomprise any of the aforementioned elements of apparatus 200. System 240may further comprise a radio frequency (RF) transceiver 244. RFtransceiver 244 may include one or more radios capable of transmittingand receiving signals using various suitable wireless communicationstechniques. Such techniques may involve communications across one ormore wireless networks. Exemplary wireless networks include (but are notlimited to) wireless local area networks (WLANs), wireless personal areanetworks (WPANs), wireless metropolitan area network (WMANs), cellularnetworks, and satellite networks. In communicating across such networks,RF transceiver 244 may operate in accordance with one or more applicablestandards in any version. In some embodiments, wireless network 250 maycomprise an 802.11 wireless network, and RF transceiver 244 may beoperative to transmit and/or receive one or more signals over wirelessnetwork 250 according to IEEE 802.11-2012 and/or IEEE 802.11ac Revision5.0, and/or according to any predecessors, revisions, or variantsthereof. The embodiments are not limited in this context.

In various embodiments, RF transceiver 244 may be coupled to an antennaarray 246 comprising one or more antennas. In some embodiments, RFtransceiver 244 may be operative to transmit and/or receive one or moresignals over wireless network 250 via antenna array 246. In variousembodiments, RF transceiver 244 may be operative to utilize antennaarray 246 to simultaneously transmit and/or receive multiple soundingpreambles. In some embodiments, RF transceiver 244 may be operative totransmit multiple sounding preambles in different respective directionsusing antenna array 246. The embodiments are not limited in thiscontext.

In general operation, apparatus 200 and/or system 240 may be operativeto communicate over wireless network 250 in order to determine anestimated location for apparatus 200 and/or system 240. In variousembodiments, for example, apparatus 200 and/or system 240 may beoperative to send timing initiation information 210 to a communicationsdevice 251 over wireless network 250, and to receive timing replyinformation 212 from the communications device 251 over the wirelessnetwork 250. In various such embodiments, apparatus 200 and/or system240 may be operative to determine times of flight 214 based on thereceived timing reply information 212, and to utilize the determinedtimes of flight 214 in conjunction with determining an estimatedlocation for apparatus 200 and/or system 240. It is worthy of note thatalthough the example of FIG. 2 depicts a single communications device251 with which apparatus 200 and/or system 240 communicates overwireless network 250, the embodiments are not so limited. In someembodiments, apparatus 200 and/or system 240 of FIG. 2 may be operativeto send timing initiation information 210 to multiple differentcommunications devices over wireless network 250, and/or to receivetiming reply information 212 from multiple communications devices overwireless network 250. The embodiments are not limited in this context.

Hereinafter, the term “timing information exchange” shall be employed todenote the collective operations comprising the transmission ofparticular timing initiation information such as timing initiationinformation 210 to a communications device such as communications device251, and the receipt of timing reply information such as timing replyinformation 212 from that communications device in response to thetiming initiation information. In various embodiments, apparatus 200and/or system 240 may be operative to perform a series of timinginformation exchanges with communications device 251, and/or with one ormore other communications devices, over wireless network 250. Theembodiments are not limited in this context.

In some embodiments, during each timing information exchange,communications management module 206 may be operative to determine oneor more local event times 211. In various embodiments, local event times211 may comprise times at which apparatus 200 and/or system 240 sent orreceived particular transmissions during that timing informationexchange. For example, for a given timing information exchange,communications management module 206 may be operative to determine afirst local event time 211 indicating a time at which transmission oftiming initiation information 210 commenced and may be operative todetermine a second local event time 211 indicating a time at whichreceipt of timing reply information 212 was completed. The embodimentsare not limited in this context.

In some embodiments, the timing reply information 212 that apparatus 200and/or system 240 receives during a given timing information exchangemay comprise one or more remote event times 213. In various embodiments,remote event times 213 may comprise times at which communications device251 sent or received particular transmissions during that timinginformation exchange. For example, for a given timing informationexchange, apparatus 200 and/or system 240 may be operative to receivetiming reply information 212 comprising a first remote event time 213indicating a time at which communications device 251 finished receivingthe timing initiation information 210 and comprising a second remoteevent time 213 indicating a time at which communications device 251began sending timing reply information 212. In some embodiments, remoteevent times 213 may alternatively or additionally comprise differencesbetween such times. For example, rather than comprising a first remoteevent time 213 indicating a time at which communications device 251finished receiving the timing initiation information 210 and a secondremote event time 213 indicating a time at which communications device251 began sending timing reply information 212, timing reply information212 may comprise a single remote event time 213 indicating a differencebetween the times of those two events. The embodiments are not limitedin this context.

In various embodiments, during each timing information exchange,apparatus 200 and/or system 240 may alternatively or additionally beoperative to receive timing reply information 212 comprising one or moreremote event times 213 corresponding to times at which communicationsdevice 251 sent or received particular transmissions during a previoustiming information exchange. In some such embodiments, during a firsttiming information exchange in a series, apparatus 200 and/or system 240may be operative to send timing initiation information 210 requestingthe determination of one or more remote event times 213, and may receivetiming reply information 212 acknowledging the request but notcomprising remote event times 213. During each subsequent timinginformation exchange in the series, apparatus 200 and/or system 240 maybe operative to receive timing reply information 212 comprising remoteevent times 213 requested in the timing initiation information 210 ofthe preceding timing information exchange in the series. The embodimentsare not limited in this context.

In various embodiments, apparatus 200 and/or system 240 may be operativeon RF transceiver 244 and antenna array 246 to transmit timinginitiation information 210 comprising multiple sounding preambles,and/or to receive timing reply information 212 comprising multiplesounding preambles. In some such embodiments, apparatus 200 and/orsystem 240 may be operative on RF transceiver 244 and antenna array 246to transmit different sounding preambles of timing initiationinformation 210 in different directions. In some embodiments, apparatus200 and/or system 240 may be operative to send any one or moreparticular sounding preambles using a combination of two or moreantennas of antenna array 246. The embodiments are not limited in thiscontext.

FIG. 3A illustrates a first embodiment 300 of a timing informationexchange that may be performed by an initiator and a responder, such asapparatus 200 and/or system 240 and communications device 251 of FIG. 2respectively, in various embodiments. As shown in FIG. 3A, the initiatorsends timing initiation information 301 to the responder. After a timeinterval 303, the responder sends timing reply information 306 to theinitiator in response to the timing initiation information 301. Theembodiments are not limited to these examples.

FIG. 3B illustrates a second embodiment 320 of a timing informationexchange that may be performed by an initiator and a responder, such asapparatus 200 and/or system 240 and communications device 251 of FIG. 2respectively, in some embodiments. More particularly, FIG. 3Billustrates elements that may comprise timing initiation information 301and timing reply information 306 of FIG. 3A in various embodiments. Inthe timing information exchange of FIG. 3B, the initiator first sends atiming announcement element 302 to the responder. In some embodiments,timing announcement element 302 may comprise logic, information, data,and/or instructions operative to notify the responder that a timingreference element 304 will be sent and to indicate to the responder thata remote event time corresponding to receipt of the timing referenceelement 304 is desired. In various embodiments, timing reference element304 may comprise an arbitrary information element in a format definedfor use in the determination of times of flight. In some embodiments,timing reference element 304 may comprise a set of one or more soundingpreambles. In various embodiments, timing reference element 304 maycomprise a null data element. Following a time interval 303, theinitiator sends the timing reference element 304 to the responder.

Following a second time interval 305, which may be the same as ordifferent than the time interval 303, the responder sends timingresponse element 310 to the initiator in response to the timingannouncement 302 and/or the timing reference element 304. In someembodiments, timing response element 310 may comprise logic,information, data, and/or instructions operative to acknowledge timingannouncement element 302 and timing reference element 304. In variousembodiments, timing response element 310 may comprise a remote eventtime corresponding to receipt of the timing reference element 304. Insome embodiments, timing response element 310 may comprise a remoteevent time corresponding to receipt of a timing reference element 304during a previous timing information exchange.

In various embodiments, timing response element 310 may indicate thatthe responder will send a timing reference element 312, which maycomprise an arbitrary information element in a same or similar format astiming reference element 304. In various embodiments, timing referenceelement 312 may comprise a null data element. In some embodiments,timing reference element 312 may comprise a set of one or more soundingpreambles. In some embodiments, timing response element 310 may comprisea remote event time indicating a time at which the timing referenceelement 312 will be sent. In various embodiments, timing responseelement 310 may comprise a remote event time indicating a time at whicha timing reference element 312 was sent during a previous timinginformation exchange. In some embodiments, timing response element 310may alternatively or additionally comprise a remote event timeindicating a difference between the time of receipt of the timingreference element 304 and the time of transmission of the timingreference element 312 during the current timing information exchange ora previous timing information exchange. Following a third time interval307, which may be the same as or different than either or both of timeintervals 303 and 305, the responder sends the timing reference element312 to the initiator. Other embodiments are described and claimed.

FIG. 3C illustrates a third embodiment 340 of a timing informationexchange that may be performed by an initiator and a responder, such asapparatus 200 and/or system 240 and communications device 251 of FIG. 2respectively, in various embodiments. More particularly, FIG. 3Cillustrates an embodiment in which the responder sends a timing responseelement 310 that contains a timing reference element 314. Unlike theexample embodiment of FIG. 3B, in which the responder sends a separatetiming reference element 312 following time interval 307, in the exampleembodiment of FIG. 3C, the responder includes the timing referenceelement 314 within the timing response element 310. Thus in the exampleof FIG. 3C, the responder performs only one transmission, while itperforms two transmissions in the example of FIG. 3B. In someembodiments, the timing reference element 314 of FIG. 3C may comprise anarbitrary information element of a different format than that of timingreference element 312 of FIG. 3B and/or timing reference element 304 ofFIGS. 3B and 3C. In some embodiments, timing reference element 314 maycomprise a set of one or more sounding preambles. The embodiments arenot limited in this context.

It is worthy of note that the various elements depicted in the exampletiming information exchange illustrations of FIGS. 3A-3C do notnecessarily comprise single spatial streams, nor do they necessarilycomprise transmissions exchanged exclusively between the initiator andthe responder. For example, in various embodiments, timing referenceelement 304 may comprise an information element sent by a combination ofantennas of antenna array 246 of FIG. 2. In another example, in someembodiments, timing announcement element 302 may comprise an informationelement broadcast to multiple communications devices using anomnidirectional antenna. The embodiments are not limited in thiscontext.

FIG. 4A illustrates a fourth embodiment 400 of a timing informationexchange that may be performed by an initiator and a responder, such asapparatus 200 and/or system 240 and communications device 251 of FIG. 2respectively, in various embodiments. More particularly, FIG. 4Aillustrates elements that may comprise timing announcement element 302,timing reference element 304, timing response element 310, and timingreference element 312 of FIG. 3B in some 802.11 embodiments. In various802.11 embodiments, the initiator may comprise a station (STA) and theresponder may comprise an access point (AP). As shown in FIG. 4A, theinitiator first sends a time of flight (ToF) announcement 402 to theresponder. ToF announcement 402 may comprise an information elementdefined for use by an initiator in an 802.11 network to initiate atiming information exchange with a responder. In some embodiments, ToFannouncement 402 may comprise a modified version of an 802.11ac nulldata packet (NDP) announcement. ToF announcement 402 may comprise one ormore timing announcement parameters such as will be discussed below withrespect to FIG. 4B. Following a short interframe space (SIFS) 405, theinitiator may send an 802.11 null data packet (NDP) 404 to theresponder. In various embodiments, the NDP 404 may comprise a first setof one or more sounding preambles. In some embodiments, each of thefirst set of sounding preambles may comprise a long training field(LTF). Following a second SIFS 405, the responder may send a ToFresponse 410 to the initiator. ToF response 410 may comprise aninformation element defined for use by a responder in an 802.11 networkto reply to a ToF announcement 402 received from an initiator in atiming information exchange, and may comprise one or more timingresponse parameters such as will be discussed below with respect to FIG.4C. Following a third SIFS 405, the responder may send an NDP 412 to theinitiator. In some embodiments, the NDP 412 may comprise a second set ofone or more sounding preambles. In some embodiments, each of the secondset of sounding preambles may comprise an LTF. The embodiments are notlimited in this context.

FIG. 4B illustrates an embodiment of a ToF announcement such as maycomprise an example of ToF announcement 402 of FIG. 4A in variousembodiments. As shown in FIG. 4B, ToF announcement 402 comprisesmultiple timing announcement parameters, including measurement requestparameter 420, measurement poll parameter 422, receive capabilitiesparameter 424, NDP bandwidth parameter 426, and sounding preamble (SP)count parameter 428. In some embodiments, measurement request parameter420 may comprise one or more bits indicating whether a time of flightmeasurement is desired. It is to be understood that such a time offlight may comprise a time of flight according to IEEE 802.11-2012, IEEE802.11ac Revision 5.0, and/or any predecessors, revisions, or variantsthereof. In various embodiments, measurement poll parameter 422 maycomprise one or more bits indicating whether a poll of a previousmeasurement is required. In some embodiments, receive capabilitiesparameter 424 may comprise one or more bits identifying a format ofsounding preambles or other timing reference elements that the initiatoris capable of properly receiving. For example, in the embodiment of FIG.4A, receive capabilities parameter 424 may comprise one or more bitsindicating that the initiator is capable of properly receiving soundingpreambles comprising NDPs such as NDP 412. In various embodiments, NDPbandwidth parameter 426 may comprise one or more bits specifying abandwidth for an NDP to be subsequently sent by the initiator. In someembodiments, SP count parameter 428 may comprise one or more bitsspecifying a number of sounding preambles to be comprised within thesubsequent NDP.

It is to be understood that ToF announcement 402 may comprise othertiming announcement parameters in various embodiments. Likewise, in someembodiments, ToF announcement 402 may not comprise all of the timingannouncement parameters illustrated in FIG. 4B. For example, in variousembodiments, ToF announcement 402 may not comprise a receivecapabilities parameter 424. The embodiments are not limited in thiscontext.

FIG. 4C illustrates an embodiment of a ToF response such as may comprisean example of ToF response 410 of FIG. 4A in some embodiments. As shownin FIG. 4C, ToF response 410 comprises multiple timing responseparameters, including ToF result parameter 430, response calculationtime parameter 432, response buffer time parameter 434, and requeststatus parameter 436. In various embodiments, ToF result parameter 430may comprise one or more bits identifying a measured difference betweena time of receipt of an NDP 404 and a time of transmission of an NDP 412by the responder, or indicating that no such difference was measured. Insome embodiments, response calculation time parameter 432 may compriseone or more bits indicating a minimum time required to generate asubsequent ToF response 410 comprising a measurement requested by ToFannouncement 402. In various embodiments, response buffer time parameter434 may comprise one or more bits indicating a maximum time that theresponder will buffer the subsequent ToF response 410 before it ispolled. In some embodiments, equal values of response calculation timeparameter 432 and response buffer time parameter 434 may collectivelyidentify a time at which the subsequent ToF response 410 will be readyand at which the subsequent ToF response 410 should be polled by theinitiator. In various embodiments, request status parameter 436 maycomprise one or more bits indicating whether the ToF announcement 402can be accepted or whether it will be deferred, due to AP overload, forexample. It is to be understood that ToF response 410 may comprise othertiming response parameters in some embodiments. Likewise, in variousembodiments, ToF response 410 may not comprise all of the timingresponse parameters illustrated in FIG. 4C. The embodiments are notlimited in this context.

FIG. 4D illustrates a transmission diagram 450 such as may comprise anexample of transmissions exchanged by an initiator and a responder insome 802.11 embodiments. More particularly, FIG. 4D illustratestransmissions that may be comprised within an initial timing informationexchange 452 and a subsequent timing information exchange 454 in various802.11 embodiments corresponding to the elements described in FIGS.4A-4C. As shown in FIG. 4D, during the initial timing informationexchange 452, the initiator may send a first ToF announcement, and thenmay send an NDP 1A at time t₁. The responder may receive the NDP 1A attime t₂. Next, the responder may send a first ToF response, in which theToF result parameter may comprise a value of zero indicating that a timeof flight measurement has not yet been performed. At time t₃, theresponder may send an NDP 1B, which the initiator may receive at timet₄.

During the subsequent timing information exchange 454, the initiator maysend a second ToF announcement, and then may send an NDP 2A at time t₁′.The responder may receive the NDP 2A at time t₂′. Next, the respondermay send a second ToF response, in which the ToF result parameter maycomprise the difference between the times t₃ and t₂ determined duringthe initial timing information exchange 452. At time t₃′, the respondermay send an NDP 2B, which the initiator may receive at time t₄′. Theinitiator may then determine a combined time of flight for NDPs 1A and1B based on the times t₁, t₂, t₃, and t₄. More particularly, theinitiator may determine the combined time of flight for NDPs 1A and 1Baccording to the equation:transit time=(t ₄ −t ₁)−(t ₃ −t ₂);  Equation (1)where (t₄−t₁) indicates the total amount of time elapsed betweentransmission of NDP 1A and receipt of NDP 1B by the initiator, and(t₃−t₂) indicates an amount of time elapsed between receipt of NDP 1Aand transmission of NDP 1B by the responder. Similarly, a combined timeof flight for NDPs 2A and 2B may be determined according to Equation (1)during a next timing information exchange, based on the times t₁′, t₂′,t₃′, and t₄′. The embodiments are not limited in this context.

FIG. 5A illustrates a fifth embodiment 500 of a timing informationexchange that may be performed by an initiator and a responder, such asapparatus 200 and/or system 240 and communications device 251 of FIG. 2respectively, in some embodiments. More particularly, FIG. 5Aillustrates elements that may comprise timing announcement element 302,timing reference element 304, timing response element 310, and timingreference element 314 of FIG. 3C in various 802.11 embodiments. Invarious 802.11 embodiments, the initiator may comprise a station (STA)and the responder may comprise an access point (AP). As shown in FIG.5A, the initiator first sends a time of flight (ToF) announcement 502 tothe responder. ToF announcement 502 may comprise an information elementdefined for use by an initiator in an 802.11 network to initiate atiming information exchange with a responder, and may be the same as orsimilar to ToF announcement 402. In some embodiments of the example ofFIG. 5A, however, the ToF announcement 502 may comprise a receivecapabilities parameter indicating that the initiator is capable ofproperly receiving timing reference elements comprising IEEE 802.11extended long training fields (eLTFs). Following a SIFS 505, theinitiator may send an 802.11 null data packet (NDP) 504 to theresponder. In various embodiments, the NDP 504 may comprise a first setof one or more sounding preambles. In some embodiments, each of thefirst set of sounding preambles may comprise an LTF. Following a secondSIFS 505, the responder may send a ToF response 510 to the initiator.Like ToF response 410 of FIG. 4A, ToF response 510 may comprise aninformation element defined for use by a responder in an 802.11 networkto reply to a ToF announcement 502 received from an initiator in atiming information exchange. In contrast to ToF response 410 of FIG. 4A,however, ToF response 510 may comprise a second set of one or moresounding preambles. The embodiments are not limited in this context.

FIG. 5B illustrates an embodiment of a ToF response such as may comprisean example of ToF response 510 of FIG. 5A in some embodiments. As shownin FIG. 5B, ToF response 510 comprises multiple timing responseparameters, including ToF result parameter 530, response calculationtime parameter 532, response buffer time parameter 534, and requeststatus parameter 536. Each of these timing response parameters may bethe same as or similar to their counterparts in ToF response 410 of FIG.4C. ToF response 510 also comprises a second set of one or more soundingpreambles comprising eLTFs 514, which may comprise an example of timingreference element 314 of FIG. 3C. In various embodiments, a respondermay be operative to generate a ToF response 510 comprising eLTFs 514when the initiator is capable of properly receiving eLTFs. For example,a responder that receives a ToF announcement in which a receivecapabilities parameter indicates that the initiator is capable ofproperly receiving eLTFs may be operative to send a ToF response 510comprising eLTFs 514. The embodiments are not limited in this context.

FIG. 5C illustrates a transmission diagram 550 such as may comprise anexample of transmissions exchanged by an initiator and a responder insome 802.11 embodiments. More particularly, FIG. 5C illustratestransmissions that may be comprised within an initial timing informationexchange 552 and a subsequent timing information exchange 554 in various802.11 embodiments corresponding to the elements described in FIGS.5A-5B. As shown in FIG. 5C, during the initial timing informationexchange 552, the initiator may send a first ToF announcement, and thenmay send an NDP 1 at time t₁. The responder may receive the NDP 1 attime t₂. Next, at time t₃, the responder may send a first ToF response,which may include one or more eLTFs and in which the ToF resultparameter may comprise a value of zero indicating that a time of flightmeasurement has not yet been performed. The initiator may receive thefirst ToF response at time t₄.

During the subsequent timing information exchange 454, the initiator maysend a second ToF announcement, and then may send an NDP 2A at time t₁′.The responder may receive the NDP 2A at time t₂′. Next, the respondermay send a second ToF response, in which the ToF result parameter maycomprise the difference between the times t₃ and t₂ determined duringthe initial timing information exchange 452. At time t₃′, the respondermay send an NDP 2B, which the initiator may receive at time t₄′. Theinitiator may then determine a combined time of flight for NDP 1 and ToFresponse 1 based on the times t₁, t₂, t₃, and t₄, according to Equation(1). Similarly, a combined time of flight for NDP 2 and ToF response 2may be determined according to Equation (1) during a next timinginformation exchange, based on the times t₁′, t₂′, t₃′, and t₄′. Theembodiments are not limited in this context.

Operations for the above embodiments may be further described withreference to the following figures and accompanying examples. Some ofthe figures may include a logic flow. Although such figures presentedherein may include a particular logic flow, it can be appreciated thatthe logic flow merely provides an example of how the generalfunctionality as described herein can be implemented. Further, the givenlogic flow does not necessarily have to be executed in the orderpresented unless otherwise indicated. In addition, the given logic flowmay be implemented by a hardware element, a software element executed bya processor, or any combination thereof. The embodiments are not limitedin this context.

FIG. 6 illustrates a block diagram of an apparatus 600. Moreparticularly, apparatus 600 may comprise an example of communicationsdevice 251 of FIG. 2 and/or responder 130 of FIG. 1 according to someembodiments. As shown in FIG. 6, apparatus 600 comprises multipleelements including a processor circuit 602, a memory unit 604, and acommunications management module 606. The embodiments, however, are notlimited to the type, number, or arrangement of elements shown in thisfigure.

In various embodiments, apparatus 600 may comprise processor circuit602. Processor circuit 602 may be implemented using any processor orlogic device, and may be the same as or similar to processor circuit 202of FIG. 2. The embodiments are not limited in this context.

In some embodiments, apparatus 600 may comprise or be arranged tocommunicatively couple with a memory unit 604. Memory unit 604 may beimplemented using any machine-readable or computer-readable mediacapable of storing data, including both volatile and non-volatilememory, and may be the same as or similar to memory unit 204 of FIG. 2.It is worthy of note that some portion or all of memory unit 604 may beincluded on the same integrated circuit as processor circuit 602, oralternatively some portion or all of memory unit 604 may be disposed onan integrated circuit or other medium, for example a hard disk drive,that is external to the integrated circuit of processor circuit 602.Although memory unit 604 is comprised within apparatus 600 in FIG. 6,memory unit 604 may be external to apparatus 600 in some embodiments.The embodiments are not limited in this context.

In various embodiments, apparatus 600 may comprise communicationsmanagement module 606. Communications management module 606 may compriselogic, circuitry, and/or instructions operative to manage and/orconfigure communications by apparatus 600 over wireless network 250 ofFIG. 2. In some embodiments, communications management module 606 mayadditionally or alternatively be operative to manage and/or configurecommunications over wireless network 250 by apparatus 200 and/or system240 of FIG. 2. The embodiments are not limited in this context.

FIG. 6 also illustrates a block diagram of a system 640. System 640 maycomprise any of the aforementioned elements of apparatus 600. System 640may further comprise a radio frequency (RF) transceiver 644. RFtransceiver 644 may include one or more radios capable of transmittingand receiving signals using various suitable wireless communicationstechniques, and may be the same as or similar to RF transceiver 244 ofFIG. 2. The embodiments are not limited in this context.

In various embodiments, RF transceiver 644 may be coupled to an antennaarray 646 comprising one or more antennas. In some embodiments, RFtransceiver 644 may be operative to transmit and/or receive one or moresignals over wireless network 650 via antenna array 646. In variousembodiments, RF transceiver 644 may be operative to utilize antennaarray 646 to simultaneously transmit and/or receive multiple soundingpreambles. In some embodiments, RF transceiver 644 may be operative totransmit multiple sounding preambles in different respective directionsusing antenna array 646. In some embodiments, apparatus 600 and/orsystem 640 may be operative to send any one or more particular soundingpreambles using a combination of two or more antennas of antenna array646. The embodiments are not limited in this context.

In general operation, apparatus 600 and/or system 640 may be operativeto communicate over wireless network 250 in order to determine anestimated location for apparatus 200 and/or system 240 of FIG. 2. Invarious embodiments, for example, apparatus 600 and/or system 640 may beoperative to receive timing initiation information 210 from apparatus200 and/or system 240 over wireless network 250, and to send timingreply information 212 to apparatus 200 and/or system 240 over thewireless network 250. In some embodiments, apparatus 600 and/or system640 may be operative to determine a time of arrival of a soundingpreamble associated with a strongest line of sight component among afirst sounding preamble set comprised in the received timing initiationinformation 210, and to generate the timing reply information 212 basedon that time of arrival. In various such embodiments, apparatus 600and/or system 640 may be operative to determine remote event times 213such as described above with respect to FIG. 2, and to send timing replyinformation 212 comprising those remote event times 213. Apparatus 200and/or system 240 of FIG. 2 may then be operative to determine times offlight 214 based on the timing reply information 212 and/or the remoteevent times 213. The embodiments are not limited in this context.

FIG. 7 illustrates one embodiment of a logic flow 700, which may berepresentative of the operations executed by one or more embodimentsdescribed herein. More particularly, logic flow 700 may berepresentative of operations execution by apparatus 200 and/or system240 of FIG. 2 according to some embodiments. As shown in logic flow 700,a timing announcement element comprising a sounding preamble countparameter may be sent at 702. For example, communications managementmodule 206 of FIG. 2 may be operative to send timing initiationinformation 210 comprising a timing announcement element including asounding preamble count parameter. At 704, a first timing referenceelement may be sent that comprises a first sounding preamble set of asize specified by the sounding preamble count parameter. For example,communications management module 206 of FIG. 2 may be operative to sendtiming initiation information 210 comprising a timing reference elementincluding a number of sounding preambles specified by the soundingpreamble count parameter. At 706, timing reply information may bereceived that comprises a second timing reference element including asecond sounding preamble set of a size specified by the soundingpreamble count parameter. For example, apparatus 200 and/or system 240of FIG. 2 may be operative to receive timing reply information 212comprising a timing reference element including a number of soundingpreambles specified by the sounding preamble count parameter. At 708, atime of flight may be determined based on the timing reply information.For example, communications management module 206 of FIG. 2 may beoperative to determine a time of flight 214 based on timing replyinformation 212. The embodiments are not limited to these examples.

FIG. 8 illustrates one embodiment of a logic flow 800, which may berepresentative of the operations executed by one or more embodimentsdescribed herein. More particularly, logic flow 800 may berepresentative of operations execution by apparatus 600 and/or system640 of FIG. 6 according to various embodiments. As shown in logic flow800, a timing announcement element comprising a sounding preamble countparameter may be received at 802. For example, apparatus 600 and/orsystem 640 of FIG. 6 may be operative to receive timing initiationinformation 210 comprising a timing announcement element including asounding preamble count parameter. At 804, a first timing referenceelement may be received that comprises a first sounding preamble set ofa size specified by the sounding preamble count parameter. For example,apparatus 600 and/or system 640 of FIG. 6 may be operative to receivetiming initiation information 210 comprising a timing reference elementincluding a number of sounding preambles specified by the soundingpreamble count parameter. At 806, timing reply information may be sentthat comprises a second timing reference element including a secondsounding preamble set of a size specified by the sounding preamble countparameter. For example, communications management module 606 of FIG. 6may be operative to send timing reply information 212 comprising atiming reference element including the number of sounding preamblesspecified by the sounding preamble count parameter. The embodiments arenot limited to these examples.

FIG. 9 illustrates an embodiment of a storage medium 900. The storagemedium 900 may comprise an article of manufacture. In one embodiment,the storage medium 900 may comprise any non-transitory computer readablemedium or machine readable medium, such as an optical, magnetic orsemiconductor storage. The storage medium may store various types ofcomputer executable instructions, such as instructions to implement oneor both of logic flows 700 and 800. Examples of a computer readable ormachine readable storage medium may include any tangible media capableof storing electronic data, including volatile memory or non-volatilememory, removable or non-removable memory, erasable or non-erasablememory, writeable or re-writeable memory, and so forth. Examples ofcomputer executable instructions may include any suitable type of code,such as source code, compiled code, interpreted code, executable code,static code, dynamic code, object-oriented code, visual code, and thelike. The embodiments are not limited in this context.

FIG. 10 illustrates an embodiment of a communications device 1000 foruse in a wireless network such as wireless network 100 of FIG. 1 and/orwireless network 250 of FIGS. 2 and 6. Device 1000 may implement, forexample, apparatus 200, system 240, apparatus 600, system 640, storagemedium 900 and/or a logic circuit 1028. The logic circuit 1028 mayinclude physical circuits to perform operations described for apparatus200 or apparatus 600, for example. As shown in FIG. 10, device 1000 mayinclude a radio interface 1010, baseband circuitry 1020, and computingplatform 1030, although the embodiments are not limited to thisconfiguration.

The device 1000 may implement some or all of the structure and/oroperations for the apparatus 200, system 240, apparatus 600, system 640,storage medium 900 and/or logic circuit 1028 in a single computingentity, such as entirely within a single device. Alternatively, thedevice 1000 may distribute portions of the structure and/or operationsfor the apparatus 200, system 240, apparatus 600, system 640, storagemedium 900 and/or logic circuit 1028 across multiple computing entitiesusing a distributed system architecture, such as a client-serverarchitecture, a 3-tier architecture, an N-tier architecture, atightly-coupled or clustered architecture, a peer-to-peer architecture,a master-slave architecture, a shared database architecture, and othertypes of distributed systems. The embodiments are not limited in thiscontext.

In one embodiment, radio interface 1010 may include a component orcombination of components adapted for transmitting and/or receivingsingle carrier or multi-carrier modulated signals (e.g., includingcomplementary code keying (CCK) and/or orthogonal frequency divisionmultiplexing (OFDM) symbols) although the embodiments are not limited toany specific over-the-air interface or modulation scheme. Radiointerface 1010 may include, for example, a receiver 1012, a frequencysynthesizer 1014, and/or a transmitter 1016. Radio interface 1010 mayinclude bias controls, a crystal oscillator and/or one or more antennas1018-f. In another embodiment, radio interface 1010 may use externalvoltage-controlled oscillators (VCOs), surface acoustic wave filters,intermediate frequency (IF) filters and/or RF filters, as desired. Dueto the variety of potential RF interface designs an expansivedescription thereof is omitted.

Baseband circuitry 1020 may communicate with radio interface 1010 toprocess receive and/or transmit signals and may include, for example, ananalog-to-digital converter 1022 for down converting received signals, adigital-to-analog converter 1024 for up converting signals fortransmission. Further, baseband circuitry 1020 may include a baseband orphysical layer (PHY) processing circuit 1026 for PHY link layerprocessing of respective receive/transmit signals. Baseband circuitry1020 may include, for example, a medium access control (MAC) processingcircuit 1027 for MAC/data link layer processing. Baseband circuitry 1020may include a memory controller 1032 for communicating with MACprocessing circuit 1027 and/or a computing platform 1030, for example,via one or more interfaces 1034.

In some embodiments, PHY processing circuit 1026 may include a frameconstruction and/or detection module, in combination with additionalcircuitry such as a buffer memory, to construct and/or deconstructcommunication frames. Alternatively or in addition, MAC processingcircuit 1027 may share processing for certain of these functions orperform these processes independent of PHY processing circuit 1026. Insome embodiments, MAC and PHY processing may be integrated into a singlecircuit.

The computing platform 1030 may provide computing functionality for thedevice 1000. As shown, the computing platform 1030 may include aprocessing component 1040. In addition to, or alternatively of, thebaseband circuitry 1020, the device 1000 may execute processingoperations or logic for the apparatus 200, system 240, apparatus 600,system 640, storage medium 900, and/or logic circuit 1028 using theprocessing component 1040. The processing component 1040 (and/or PHY1026 and/or MAC 1027) may comprise various hardware elements, softwareelements, or a combination of both. Examples of hardware elements mayinclude devices, logic devices, components, processors, microprocessors,circuits, processor circuits (e.g., processor circuit 120), circuitelements (e.g., transistors, resistors, capacitors, inductors, and soforth), integrated circuits, application specific integrated circuits(ASIC), programmable logic devices (PLD), digital signal processors(DSP), field programmable gate array (FPGA), memory units, logic gates,registers, semiconductor device, chips, microchips, chip sets, and soforth. Examples of software elements may include software components,programs, applications, computer programs, application programs, systemprograms, software development programs, machine programs, operatingsystem software, middleware, firmware, software modules, routines,subroutines, functions, methods, procedures, software interfaces,application program interfaces (API), instruction sets, computing code,computer code, code segments, computer code segments, words, values,symbols, or any combination thereof. Determining whether an embodimentis implemented using hardware elements and/or software elements may varyin accordance with any number of factors, such as desired computationalrate, power levels, heat tolerances, processing cycle budget, input datarates, output data rates, memory resources, data bus speeds and otherdesign or performance constraints, as desired for a givenimplementation.

The computing platform 1030 may further include other platformcomponents 1050. Other platform components 1050 include common computingelements, such as one or more processors, multi-core processors,co-processors, memory units, chipsets, controllers, peripherals,interfaces, oscillators, timing devices, video cards, audio cards,multimedia input/output (I/O) components (e.g., digital displays), powersupplies, and so forth. Examples of memory units may include withoutlimitation various types of computer readable and machine readablestorage media in the form of one or more higher speed memory units, suchas read-only memory (ROM), random-access memory (RAM), dynamic RAM(DRAM), Double-Data-Rate DRAM (DDRAM), synchronous DRAM (SDRAM), staticRAM (SRAM), programmable ROM (PROM), erasable programmable ROM (EPROM),electrically erasable programmable ROM (EEPROM), flash memory, polymermemory such as ferroelectric polymer memory, ovonic memory, phase changeor ferroelectric memory, silicon-oxide-nitride-oxide-silicon (SONOS)memory, magnetic or optical cards, an array of devices such as RedundantArray of Independent Disks (RAID) drives, solid state memory devices(e.g., USB memory, solid state drives (SSD) and any other type ofstorage media suitable for storing information.

Device 1000 may be, for example, an ultra-mobile device, a mobiledevice, a fixed device, a machine-to-machine (M2M) device, a personaldigital assistant (PDA), a mobile computing device, a smart phone, atelephone, a digital telephone, a cellular telephone, user equipment,eBook readers, a handset, a one-way pager, a two-way pager, a messagingdevice, a computer, a personal computer (PC), a desktop computer, alaptop computer, a notebook computer, a netbook computer, a handheldcomputer, a tablet computer, a server, a server array or server farm, aweb server, a network server, an Internet server, a work station, amini-computer, a main frame computer, a supercomputer, a networkappliance, a web appliance, a distributed computing system,multiprocessor systems, processor-based systems, consumer electronics,programmable consumer electronics, game devices, television, digitaltelevision, set top box, wireless access point, base station, node B,subscriber station, mobile subscriber center, radio network controller,router, hub, gateway, bridge, switch, machine, or combination thereof.Accordingly, functions and/or specific configurations of device 1000described herein, may be included or omitted in various embodiments ofdevice 1000, as suitably desired.

Embodiments of device 1000 may be implemented using single input singleoutput (SISO) architectures. However, certain implementations mayinclude multiple antennas (e.g., antennas 1018-f) for transmissionand/or reception using adaptive antenna techniques for beamforming orspatial division multiple access (SDMA) and/or using MIMO communicationtechniques.

The components and features of device 1000 may be implemented using anycombination of discrete circuitry, application specific integratedcircuits (ASICs), logic gates and/or single chip architectures. Further,the features of device 1000 may be implemented using microcontrollers,programmable logic arrays and/or microprocessors or any combination ofthe foregoing where suitably appropriate. It is noted that hardware,firmware and/or software elements may be collectively or individuallyreferred to herein as “logic” or “circuit.”

It should be appreciated that the exemplary device 1000 shown in theblock diagram of FIG. 10 may represent one functionally descriptiveexample of many potential implementations. Accordingly, division,omission or inclusion of block functions depicted in the accompanyingfigures does not infer that the hardware components, circuits, softwareand/or elements for implementing these functions would be necessarily bedivided, omitted, or included in embodiments.

Various embodiments may be implemented using hardware elements, softwareelements, or a combination of both. Examples of hardware elements mayinclude processors, microprocessors, circuits, circuit elements (e.g.,transistors, resistors, capacitors, inductors, and so forth), integratedcircuits, application specific integrated circuits (ASIC), programmablelogic devices (PLD), digital signal processors (DSP), field programmablegate array (FPGA), logic gates, registers, semiconductor device, chips,microchips, chip sets, and so forth. Examples of software may includesoftware components, programs, applications, computer programs,application programs, system programs, machine programs, operatingsystem software, middleware, firmware, software modules, routines,subroutines, functions, methods, procedures, software interfaces,application program interfaces (API), instruction sets, computing code,computer code, code segments, computer code segments, words, values,symbols, or any combination thereof. Determining whether an embodimentis implemented using hardware elements and/or software elements may varyin accordance with any number of factors, such as desired computationalrate, power levels, heat tolerances, processing cycle budget, input datarates, output data rates, memory resources, data bus speeds and otherdesign or performance constraints.

One or more aspects of at least one embodiment may be implemented byrepresentative instructions stored on a machine-readable medium whichrepresents various logic within the processor, which when read by amachine causes the machine to fabricate logic to perform the techniquesdescribed herein. Such representations, known as “IP cores” may bestored on a tangible, machine readable medium and supplied to variouscustomers or manufacturing facilities to load into the fabricationmachines that actually make the logic or processor. Some embodiments maybe implemented, for example, using a machine-readable medium or articlewhich may store an instruction or a set of instructions that, ifexecuted by a machine, may cause the machine to perform a method and/oroperations in accordance with the embodiments. Such a machine mayinclude, for example, any suitable processing platform, computingplatform, computing device, processing device, computing system,processing system, computer, processor, or the like, and may beimplemented using any suitable combination of hardware and/or software.The machine-readable medium or article may include, for example, anysuitable type of memory unit, memory device, memory article, memorymedium, storage device, storage article, storage medium and/or storageunit, for example, memory, removable or non-removable media, erasable ornon-erasable media, writeable or re-writeable media, digital or analogmedia, hard disk, floppy disk, Compact Disk Read Only Memory (CD-ROM),Compact Disk Recordable (CD-R), Compact Disk Rewriteable (CD-RW),optical disk, magnetic media, magneto-optical media, removable memorycards or disks, various types of Digital Versatile Disk (DVD), a tape, acassette, or the like. The instructions may include any suitable type ofcode, such as source code, compiled code, interpreted code, executablecode, static code, dynamic code, encrypted code, and the like,implemented using any suitable high-level, low-level, object-oriented,visual, compiled and/or interpreted programming language.

The following examples pertain to further embodiments:

Example 1 is at least one machine-readable medium comprising a pluralityof wireless network location instructions that, in response to beingexecuted on a computing device, cause the computing device to: send atiming announcement element comprising a sounding preamble countparameter; send a first timing reference element comprising a firstsounding preamble set of a size specified by the sounding preamble countparameter; receive timing reply information comprising a second timingreference element comprising a second sounding preamble set of the sizespecified by the sounding preamble count parameter; and determine a timeof flight based on the timing reply information.

In Example 2, the at least one machine-readable medium of Example 1 mayoptionally comprise wireless network location instructions that, inresponse to being executed on a computing device, cause the computingdevice to cause transmission of at least one sounding preamble among thefirst sounding preamble set by a combination of two or more antennas.

In Example 3, the at least one machine-readable medium of any one ofExamples 1 to 2 may optionally comprise wireless network locationinstructions that, in response to being executed on a computing device,cause the computing device to: send the first timing reference elementto a remote computing device, the first timing reference elementcomprising a bandwidth specified by a bandwidth parameter in the timingannouncement element; and receive the second timing reference elementfrom the remote computing device, the second timing reference elementcomprising the bandwidth specified by the bandwidth parameter.

In Example 4, the first timing reference element of any one of Examples1 to 3 may optionally comprise a null data packet.

In Example 5, the first sounding preamble set of any one of Examples 1to 4 may optionally comprise one or more long training fields.

In Example 6, the second timing reference element of any one of Examples1 to 5 may optionally comprise a null data packet.

In Example 7, the second sounding preamble set of any one of Examples 1to 6 may optionally comprise one or more long training fields.

In Example 8, the second sounding preamble set of any one of Examples 1to 5 may optionally comprise one or more extended long training fields.

In Example 9, the timing announcement element of any one of Examples 1to 8 may optionally comprise a receive capabilities parameter indicatinga sounding preamble format for the second sounding preamble set.

In Example 10 the at least one machine-readable medium any one ofExamples 1 to 9 may optionally comprise wireless network locationinstructions that, in response to being executed on a computing device,cause the computing device to cause transmission of each soundingpreamble in the first sounding preamble set using a different antenna.

Example 11 is a wireless network location apparatus, comprising:circuitry; and a communications management module for execution on thecircuitry to send a timing announcement element comprising a soundingpreamble count parameter indicating a number of sounding preambles, senda null data element comprising a number of sounding preambles equal tothe sounding preamble count parameter, receive timing reply informationcomprising the number of sounding preambles equal to the soundingpreamble count parameter, and determine a time of flight based on thetiming reply information.

In Example 12, the communications management module of Example 11 mayoptionally be for execution on the circuitry to cause transmission of atleast one sounding preamble by a combination of two or more antennas.

In Example 13, the communications management module of any one ofExamples 11 to 12 may optionally be for execution on the circuitry todetermine a bandwidth parameter indicating a bandwidth for the null dataelement, send the bandwidth parameter to a remote computing device, sendthe null data element based on the bandwidth parameter, and receive atiming reference element comprising the bandwidth indicated by thebandwidth parameter from the remote computing device.

In Example 14, the timing reply information of any one of Examples 11 to13 may optionally comprise a number of extended long training fieldsequal to the sounding preamble count parameter.

In Example 15, the sounding preambles of the timing reply information ofany one of Examples 11 to 13 may optionally comprise one or more longtraining fields.

In Example 16, the sounding preambles of the null data element of anyone of Examples 11 to 15 may optionally comprise one or more longtraining fields.

In Example 17, the sounding preambles of the timing reply information ofany one of Examples 11 to 16 may optionally be comprised in a timingresponse element.

In Example 18, the sounding preambles of the timing reply information ofany one of Examples 11 to 17 may optionally be comprised in a null datapacket.

In Example 19, the timing reply information of any one of Examples 11 to18 may optionally comprise a response buffer time parameter indicating amaximum time that a subsequent timing response element will be buffered.

In Example 20, the wireless network location apparatus of any one ofExamples 11 to 19 may optionally comprise an antenna array, and thecommunications management module may optionally be for execution on thecircuitry to cause transmission of each sounding preamble in the nulldata element using a different antenna of the antenna array.

In Example 21, a wireless network location apparatus comprises: meansfor sending a timing announcement element comprising a sounding preamblecount parameter; means for sending a first timing reference elementcomprising a first sounding preamble set of a size specified by thesounding preamble count parameter; means for receiving timing replyinformation comprising a second timing reference element comprising asecond sounding preamble set of the size specified by the soundingpreamble count parameter; and means for determining, by a processorcircuit, a time of flight based on the timing reply information.

In Example 22, the wireless network location apparatus of Example 21 mayoptionally comprise means for transmitting at least one soundingpreamble among the first sounding preamble set by a combination of twoor more antennas.

In Example 23, the wireless network location apparatus of any one ofExamples 21 to 22 may optionally comprise: means for sending the firsttiming reference element to a remote computing device, the first timingreference element comprising a bandwidth specified by a bandwidthparameter in the timing announcement element; and means for receivingthe second timing reference element from the remote computing device,the second timing reference element comprising the bandwidth specifiedby the bandwidth parameter.

In Example 24, the first timing reference element of any one of Examples21 to 23 may optionally comprise a null data packet.

In Example 25, the first sounding preamble set of any one of Examples 21to 24 may optionally comprise one or more long training fields.

In Example 26, the second timing reference element of any one ofExamples 21 to 25 may optionally comprise a null data packet.

In Example 27, the second sounding preamble set of any one of Examples21 to 26 may optionally comprise one or more long training fields.

In Example 28, the second sounding preamble set of any one of Examples21 to 25 may optionally comprise one or more extended long trainingfields.

In Example 29, the timing announcement element of any one of Examples 21to 28 may optionally comprise a receive capabilities parameterindicating a sounding preamble format for the second sounding preambleset.

In Example 30, the wireless network location apparatus of any one ofExamples 21 to 29 may optionally comprise means for transmitting eachsounding preamble in the first sounding preamble set using a differentantenna.

In Example 31, a wireless network location method comprises: sending atiming announcement element comprising a sounding preamble countparameter; sending a first timing reference element comprising a firstsounding preamble set of a size specified by the sounding preamble countparameter; receiving timing reply information comprising a second timingreference element comprising a second sounding preamble set of the sizespecified by the sounding preamble count parameter; and determining, bya processor circuit, a time of flight based on the timing replyinformation.

In Example 32, the wireless network location method of Example 31 mayoptionally comprise transmitting at least one sounding preamble amongthe first sounding preamble set by a combination of two or moreantennas.

In Example 33, the wireless network location method of any one ofExamples 31 to 32 may optionally comprise: sending the first timingreference element to a remote computing device, the first timingreference element comprising a bandwidth specified by a bandwidthparameter in the timing announcement element; and receiving the secondtiming reference element from the remote computing device, the secondtiming reference element comprising the bandwidth specified by thebandwidth parameter.

In Example 34, the first timing reference element of any one of Examples31 to 33 may optionally comprise a null data packet.

In Example 35, the first sounding preamble set of any one of Examples 31to 34 may optionally comprise one or more long training fields.

In Example 36, the second timing reference element of any one ofExamples 31 to 35 may optionally comprise a null data packet.

In Example 37, the second sounding preamble set of any one of Examples31 to 36 may optionally comprise one or more long training fields.

In Example 38, the second sounding preamble set of any one of Examples31 to 35 may optionally comprise one or more extended long trainingfields.

In Example 39, the timing announcement element of any one of Examples 31to 38 may optionally comprise a receive capabilities parameterindicating a sounding preamble format for the second sounding preambleset.

In Example 40, the wireless network location method of any one ofExamples 31 to 39 may optionally comprise transmitting each soundingpreamble in the first sounding preamble set using a different antenna.

In Example 41, at least one machine-readable medium may optionallycomprise a plurality of instructions that, in response to being executedon a computing device, cause the computing device to perform a wirelessnetwork location method according to any one of Examples 31 to 40.

In Example 42, an apparatus may optionally comprise means for performinga wireless network location method according to any one of Examples 31to 40.

In Example 43, a communications device may optionally be arranged toperform a wireless network location method according to any one ofExamples 31 to 40.

In Example 44, at least one machine-readable medium comprising aplurality of wireless network location instructions that, in response tobeing executed on a computing device, cause the computing device to:receive a timing announcement element comprising a sounding preamblecount parameter; receive a first timing reference element comprising afirst sounding preamble set of a size specified by the sounding preamblecount parameter; and send timing reply information comprising a secondtiming reference element comprising a second sounding preamble set ofthe size specified by the sounding preamble count parameter.

In Example 45, the at least one machine-readable medium of Example 44may optionally comprise wireless network location instructions that, inresponse to being executed on a computing device, cause the computingdevice to: determine a time of arrival of a sounding preamble associatedwith a strongest line of sight component among the first soundingpreamble set; and generate the timing reply information based on thetime of arrival.

In Example 46, the timing announcement element of any one of Examples 44to 45 may optionally comprise a bandwidth parameter, and the firsttiming reference element and the second timing reference element mayeach comprise a bandwidth specified by the bandwidth parameter.

In Example 47, the second sounding preamble set of any one of Examples44 to 46 may optionally comprise a set of extended long training fields.

In Example 48, the first timing reference element of any one of Examples44 to 47 may optionally comprise a null data packet.

In Example 49, the second timing reference element of any one ofExamples 44 to 48 may optionally comprise a null data packet.

In Example 50, the first sounding preamble set of any one of Examples 44to 49 may optionally comprise one or more long training fields.

In Example 51, the second sounding preamble set of any one of Examples44 to 50 may optionally comprise one or more long training fields.

In Example 52, the timing announcement element of any one of Examples 44to 51 may optionally comprise a receive capabilities parameterindicating a sounding preamble format for the second sounding preambleset.

In Example 53, the at least one machine-readable medium of any one ofExamples 44 to 52 may optionally comprise wireless network locationinstructions that, in response to being executed on a computing device,cause the computing device to cause transmission of each soundingpreamble in the second sounding preamble set using a different antenna.

Example 54 is a wireless network location apparatus, comprising:circuitry; and a communications management module for execution on thecircuitry to receive a timing announcement element comprising a soundingpreamble count parameter indicating a number of sounding preambles and areceive capabilities parameter indicating a sounding preamble format,receive a null data element comprising a number of sounding preamblesequal to the sounding preamble count parameter, and send timing replyinformation comprising a set of sounding preambles of the soundingpreamble format indicated by the receive capabilities parameter, the setof sounding preambles comprising a number of sounding preambles equal tothe sounding preamble count parameter.

In Example 55, the communications management module may optionally befor execution on the circuitry to determine a time of arrival of asounding preamble associated with a strongest line of sight componentamong the sounding preambles comprised in the null data element, andgenerate the timing reply information based on the time of arrival.

In Example 56, the timing announcement element of any one of Examples 54to 55 may optionally comprise a bandwidth parameter, and the null dataelement may optionally comprise a bandwidth specified by the bandwidthparameter.

In Example 57, the set of sounding preambles of any one of Examples 54to 56 may optionally comprise a set of long training fields.

In Example 58, the sounding preambles of the timing reply information ofany one of Examples 54 to 57 may optionally be comprised in a null datapacket.

In Example 59, the set of sounding preambles of any one of Examples 54to 58 may optionally comprise a set of extended long training fields.

In Example 60, the communications management module of any one ofExamples 54 to 59 may optionally be for execution on the circuitry tocause transmission of at least one sounding preamble by a combination oftwo or more antennas.

In Example 61, the sounding preambles of the null data element of anyone of Examples 54 to 60 may optionally comprise one or more longtraining fields.

In Example 62, the timing reply information of any one of Examples 54 to61 may optionally comprise a response buffer time parameter indicating amaximum time that a subsequent timing response element will be buffered.

In Example 63, the wireless network location apparatus of any one ofExamples 54 to 62 may optionally comprise an antenna array, and thecommunications management module may optionally be for execution on thecircuitry to cause transmission of each sounding preamble in the set ofsounding preambles using a different antenna of the antenna array.

In Example 64, a wireless network location apparatus comprises: meansfor receiving a timing announcement element comprising a soundingpreamble count parameter; means for receiving a first timing referenceelement comprising a first sounding preamble set of a size specified bythe sounding preamble count parameter; and means for sending timingreply information comprising a second timing reference elementcomprising a second sounding preamble set of the size specified by thesounding preamble count parameter.

In Example 65, the wireless network location apparatus of Example 64 mayoptionally comprise: means for determining a time of arrival of asounding preamble associated with a strongest line of sight componentamong the first sounding preamble set; and means for generating thetiming reply information based on the time of arrival.

In Example 66, the timing announcement element of any one of Examples 64to 65 may optionally comprise a bandwidth parameter, and the firsttiming reference element and the second timing reference element mayeach comprise a bandwidth specified by the bandwidth parameter.

In Example 67, the second sounding preamble set of any one of Examples64 to 66 may optionally comprise a set of extended long training fields.

In Example 68, the first timing reference element of any one of Examples64 to 67 may optionally comprise a null data packet.

In Example 69, the second timing reference element of any one ofExamples 64 to 68 may optionally comprise a null data packet.

In Example 70, the first sounding preamble set of any one of Examples 64to 69 may optionally comprise one or more long training fields.

In Example 71, the second sounding preamble set of any one of Examples64 to 70 may optionally comprise one or more long training fields.

In Example 72, the timing announcement element of any one of Examples 64to 71 may optionally comprise a receive capabilities parameterindicating a sounding preamble format for the second sounding preambleset.

In Example 73, the wireless network location apparatus of any one ofExamples 64 to 72 may optionally comprise means for transmitting eachsounding preamble in the second sounding preamble set using a differentantenna.

Example 74 is a wireless network location method, comprising: receivinga timing announcement element comprising a sounding preamble countparameter; receiving a first timing reference element comprising a firstsounding preamble set of a size specified by the sounding preamble countparameter; and sending timing reply information comprising a secondtiming reference element comprising a second sounding preamble set ofthe size specified by the sounding preamble count parameter.

In Example 75, the wireless network location method of Example 74 mayoptionally comprise: determining a time of arrival of a soundingpreamble associated with a strongest line of sight component among thefirst sounding preamble set; and generating the timing reply informationbased on the time of arrival.

In Example 76, the timing announcement element of any one of Examples 74to 75 may optionally comprise a bandwidth parameter, and the firsttiming reference element and the second timing reference element mayeach comprise a bandwidth specified by the bandwidth parameter.

In Example 77, the second sounding preamble set of any one of Examples74 to 76 may optionally comprise a set of extended long training fields.

In Example 78, the first timing reference element of any one of Examples74 to 77 may optionally comprise a null data packet.

In Example 79, the second timing reference element of any one ofExamples 74 to 78 may optionally comprise a null data packet.

In Example 80, the first sounding preamble set of any one of Examples 74to 79 may optionally comprise one or more long training fields.

In Example 81, the second sounding preamble set of any one of Examples74 to 80 may optionally comprise one or more long training fields.

In Example 82, the timing announcement element of any one of Examples 74to 81 may optionally comprise a receive capabilities parameterindicating a sounding preamble format for the second sounding preambleset.

In Example 83, the wireless network location method of any one ofExamples 74 to 82 may optionally comprise transmitting each soundingpreamble in the second sounding preamble set using a different antenna.

In Example 84, at least one machine-readable medium may optionallycomprise a plurality of instructions that, in response to being executedon a computing device, cause the computing device to perform a wirelessnetwork location method according to any one of claims 74 to 83.

In Example 85, an apparatus, may optionally comprise means forperforming a wireless network location method according to any one ofclaims 74 to 83.

In Example 86, a communications device may optionally be arranged toperform a wireless network location method according to any one ofclaims 74 to 83.

Numerous specific details have been set forth herein to provide athorough understanding of the embodiments. It will be understood bythose skilled in the art, however, that the embodiments may be practicedwithout these specific details. In other instances, well-knownoperations, components, and circuits have not been described in detailso as not to obscure the embodiments. It can be appreciated that thespecific structural and functional details disclosed herein may berepresentative and do not necessarily limit the scope of theembodiments.

Some embodiments may be described using the expression “coupled” and“connected” along with their derivatives. These terms are not intendedas synonyms for each other. For example, some embodiments may bedescribed using the terms “connected” and/or “coupled” to indicate thattwo or more elements are in direct physical or electrical contact witheach other. The term “coupled,” however, may also mean that two or moreelements are not in direct contact with each other, but yet stillco-operate or interact with each other.

Unless specifically stated otherwise, it may be appreciated that termssuch as “processing,” “computing,” “calculating,” “determining,” or thelike, refer to the action and/or processes of a computer or computingsystem, or similar electronic computing device, that manipulates and/ortransforms data represented as physical quantities (e.g., electronic)within the computing system's registers and/or memories into other datasimilarly represented as physical quantities within the computingsystem's memories, registers or other such information storage,transmission or display devices. The embodiments are not limited in thiscontext.

It should be noted that the methods described herein do not have to beexecuted in the order described, or in any particular order. Moreover,various activities described with respect to the methods identifiedherein can be executed in serial or parallel fashion.

Although specific embodiments have been illustrated and describedherein, it should be appreciated that any arrangement calculated toachieve the same purpose may be substituted for the specific embodimentsshown. This disclosure is intended to cover any and all adaptations orvariations of various embodiments. It is to be understood that the abovedescription has been made in an illustrative fashion, and not arestrictive one. Combinations of the above embodiments, and otherembodiments not specifically described herein will be apparent to thoseof skill in the art upon reviewing the above description. Thus, thescope of various embodiments includes any other applications in whichthe above compositions, structures, and methods are used.

It is emphasized that the Abstract of the Disclosure is provided tocomply with 37 C.F.R. §1.72(b), requiring an abstract that will allowthe reader to quickly ascertain the nature of the technical disclosure.It is submitted with the understanding that it will not be used tointerpret or limit the scope or meaning of the claims. In addition, inthe foregoing Detailed Description, it can be seen that various featuresare grouped together in a single embodiment for the purpose ofstreamlining the disclosure. This method of disclosure is not to beinterpreted as reflecting an intention that the claimed embodimentsrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive subject matter lies in lessthan all features of a single disclosed embodiment. Thus the followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separate preferred embodiment. In theappended claims, the terms “including” and “in which” are used as theplain-English equivalents of the respective terms “comprising” and“wherein,” respectively. Moreover, the terms “first,” “second,” and“third,” etc. are used merely as labels, and are not intended to imposenumerical requirements on their objects.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

The invention claimed is:
 1. At least one non-transitorymachine-readable medium comprising a plurality of wireless networklocation instructions that, in response to being executed on a computingdevice, cause the computing device to: send a timing announcementelement comprising a sounding preamble count parameter; send a firsttiming reference element comprising a first sounding preamble set of asize specified by the sounding preamble count parameter; receive timingreply information comprising a second timing reference elementcomprising a second sounding preamble set of the size specified by thesounding preamble count parameter and a response buffer time parameterthat indicates a maximum buffering time that a subsequent timingresponse element will be buffered; and determine a time of flight basedon the timing reply information.
 2. The at least one non-transitorymachine-readable medium of claim 1, comprising wireless network locationinstructions that, in response to being executed on a computing device,cause the computing device to cause transmission of at least onesounding preamble among the first sounding preamble set by a combinationof two or more antennas.
 3. The at least one non-transitorymachine-readable medium of claim 1, comprising wireless network locationinstructions that, in response to being executed on a computing device,cause the computing device to: send the first timing reference elementto a remote computing device, the first timing reference elementcomprising a bandwidth specified by a bandwidth parameter in the timingannouncement element; and receive the second timing reference elementfrom the remote computing device, the second timing reference elementcomprising the bandwidth specified by the bandwidth parameter.
 4. The atleast one non-transitory machine-readable medium of claim 1, the firsttiming reference element comprising a null data packet.
 5. The at leastone non-transitory machine-readable medium of claim 1, the second timingreference element comprising a null data packet.
 6. The at least onenon-transitory machine-readable medium of claim 1, the first soundingpreamble set comprising one or more long training fields.
 7. The atleast one non-transitory machine-readable medium of claim 1, the secondsounding preamble set comprising one or more extended long trainingfields.
 8. The at least one non-transitory machine-readable medium ofclaim 1, the timing announcement element comprising a receivecapabilities parameter indicating a sounding preamble format for thesecond sounding preamble set.
 9. A wireless network location apparatus,comprising: circuitry; and a communications management module forexecution on the circuitry to send a timing announcement elementcomprising a sounding preamble count parameter indicating a number ofsounding preambles, send a null data element comprising a number ofsounding preambles equal to the sounding preamble count parameter,receive timing reply information comprising the number of soundingpreambles equal to the sounding preamble count parameter and a responsebuffer time parameter that indicates a maximum buffering time that asubsequent timing response element will be buffered, and determine atime of flight based on the timing reply information.
 10. The wirelessnetwork location apparatus of claim 9, the communications managementmodule for execution on the circuitry to cause transmission of at leastone sounding preamble by a combination of two or more antennas.
 11. Thewireless network location apparatus of claim 9, the communicationsmanagement module for execution on the circuitry to determine abandwidth parameter indicating a bandwidth for the null data element,send the bandwidth parameter to a remote computing device, send the nulldata element based on the bandwidth parameter, and receive a timingreference element comprising the bandwidth indicated by the bandwidthparameter from the remote computing device.
 12. The wireless networklocation apparatus of claim 9, the timing reply information comprising anumber of extended long training fields equal to the sounding preamblecount parameter.
 13. The wireless network location apparatus of claim 9,the sounding preambles of the null data element comprising one or morelong training fields.
 14. The wireless network location apparatus ofclaim 9, the sounding preambles of the timing reply informationcomprised in the timing response element.
 15. The wireless networklocation apparatus of claim 9, the sounding preambles of the timingreply information comprised in a null data packet.
 16. The wirelessnetwork location apparatus of claim 9, comprising an antenna array, thecommunications management module for execution on the circuitry to causetransmission of each sounding preamble in the null data element using adifferent antenna of the antenna array.
 17. A wireless network locationmethod, comprising: sending a timing announcement element comprising asounding preamble count parameter; sending a first timing referenceelement comprising a first sounding preamble set of a size specified bythe sounding preamble count parameter; receiving timing replyinformation comprising a second timing reference element comprising asecond sounding preamble set of the size specified by the soundingpreamble count parameter and a response buffer time parameter thatindicates a maximum buffering time that a subsequent timing responseelement will be buffered; and determining, by a processor circuit, atime of flight based on the timing reply information.
 18. The wirelessnetwork location method of claim 17, comprising transmitting at leastone sounding preamble among the first sounding preamble set by acombination of two or more antennas.
 19. The wireless network locationmethod of claim 17, comprising: sending the first timing referenceelement to a remote computing device, the first timing reference elementcomprising a bandwidth specified by a bandwidth parameter in the timingannouncement element; and receiving the second timing reference elementfrom the remote computing device, the second timing reference elementcomprising the bandwidth specified by the bandwidth parameter.
 20. Thewireless network location method of claim 17, the first timing referenceelement comprising a null data packet.
 21. The wireless network locationmethod of claim 17, the second timing reference element comprising anull data packet.
 22. The wireless network location method of claim 17,the first sounding preamble set comprising one or more long trainingfields.
 23. The wireless network location method of claim 17, the secondsounding preamble set comprising one or more extended long trainingfields.
 24. The wireless network location method of claim 17, comprisingtransmitting each sounding preamble in the first sounding preamble setusing a different antenna.